Ferritic stainless steel sheet

ABSTRACT

Provided is a ferritic stainless steel sheet having excellent corrosion resistance and workability equal to or better than SUH409L. The ferritic stainless steel sheet contains 0.025% or less C, 0.01% to 1.00% Si, 0.05% to 1.00% Mn, 0.020% to 0.040% P, 0.030% or less S, 0.001% to 0.100% Al, 12.5% to 14.4% Cr, 0.01% to 0.80% Ni, 0.11% to 0.40% Ti, 0.010% to 0.100% Nb, and 0.020% or less N by mass %, the remainder being Fe and inevitable impurities.

TECHNICAL FIELD

This application relates to a ferritic stainless steel sheet havingexcellent workability equal to or better than SUH409L and excellentcorrosion resistance.

BACKGROUND

Ferritic stainless steels have excellent corrosion resistance, areresource-saving, and therefore are used for various applications such asautomotive exhaust parts, building materials, kitchen equipment, andhome appliance parts. The most important alloy element contained in theferritic stainless steels is Cr. In general, an increase in Cr contentincreases the corrosion resistance and deteriorates the workability.Because of this feature, the following steels are often separately useddepending on applications: low-Cr steels (a typical steel type isSUH409L (Japanese Industrial Standards JIS G 4312:2011, 11 mass percentCr-0.3 mass percent Ti)) which have excellent workability and inferiorcorrosion resistance and medium-Cr steels (a typical steel type isSUS430 (Japanese Industrial Standards JIS G 4305:2012, 16 mass percentCr)) which have inferior workability and excellent corrosion resistance.

In recent years, as the design of home appliances has been diversified,parts with a complicated shape have been developed. Among these, if aferritic stainless steel is applied to parts particularly required tohave corrosion resistance, maintenance is not necessary over a longperiod and life-cycle costs can be reduced. From the viewpoint offorming a complicated shape, the use of SUH409L, which has excellentworkability, is probably adequate. However, SUH409L is insufficient incorrosion resistance and therefore it is difficult to apply SUH409L tothe above parts. Hence, a ferritic stainless steel having excellentworkability equal to or better than SUH409L and excellent corrosionresistance.

Patent Literatures and 2 describe the improvement of corrosionresistance and workability. Patent Literature 1 discloses a high-purityferritic stainless steel having excellent surface properties andexcellent corrosion resistance. In Patent Literature 1, the improvementof corrosion resistance is achieved by controlling the morphology of Tiprecipitates.

Patent Literature 2 discloses a ferritic stainless steel sheet withexcellent ductility. In Patent Literature 2, the improvement ofelongation is achieved by controlling the morphology of Mg inclusions orTi carbosulfides.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No.2001-288544

[PTL 2] Japanese Unexamined Patent Application Publication No.2001-294990

SUMMARY Technical Problem

However, in Patent Literature 1, although the pitting potential, whichis an indicator for corrosion resistance, is investigated, workabilityincluding total elongation and r-value is not investigated. In PatentLiterature 2, although the product elongation (elongation afterfracture), which is an indicator for workability, is investigated,corrosion resistance is not investigated. As described in theseliteratures, examples of studies focused on both corrosion resistanceand workability are very rare among existing studies on ferriticstainless steels.

The disclosed embodiments provide a ferritic stainless steel havingexcellent workability equal to or better than SUH409L and excellentcorrosion resistance.

Solution to Problem

In order to cope with the above problem, the inventors have performedcomprehensive investigations for satisfying both corrosion resistanceand workability.

First, the inventors have found that the corrosion resistance can beimproved by containing Ti and Nb in combination. This effect is obtainedwhen the content of Ti is 0.11% to 0.40% and the content of Nb is 0.010%to 0.100%. It has become clear that this allows excellent corrosionresistance to be obtained in a ferritic stainless steel containing 12.5%or more Cr. Incidentally, the unit “%” used to express the contentrefers to “mass percent”.

Furthermore, the inventors have found that containing 0.010% to 0.100%Nb is effective in improving the workability. Containing Nb has theeffect of fining its crystal gains by existing as solid solution insteel. Since {111} <001>-oriented grains are likely to be formed fromthe local areas near grain boundaries, the proportion of recrystallizedgrains in the {11} plane increases in the recrystallization process dueto fining crystal grain by containing Nb. Since this increase suppressesthe formation of the Goss ({110} <001>)-oriented grains, which increasesin-plane anisotropy of a microstructure, the in-plane anisotropy of amicrostructure is reduced and El_(min) (the minimum of El) and r_(min)(the minimum of r) are increased. It has become clear that workabilityequal better than SUH409L is obtained in a ferritic stainless steelcontaining 14.4% or less Cr by this effect.

The investigation of both corrosion resistance and workability asdescribed above has revealed that in order to achieve a ferriticstainless steel having excellent corrosion resistance and workabilityequal to or better than SUH409L, it is very important that a ferriticstainless steel containing 12.5% to 14.4% Cr contains 0.11% to 0.40% Tiand 0.010% to 0.100% Nb.

The disclosed embodiments are based on the above findings and are assummarized below.

{1} A ferritic: stainless steel sheet contains 0.0250 or less C, 0.0% to1.00% Si, 0.05% to 1.00% Mn, 0.020% to 0.040% P, 0.030% or less S,0.001% to 0.100% Al, 12.5% to 14.4% Cr, 0.01 to 0.80fl Ni, 0.11% to0.40% Ti, 0.010% to 0.100% Nb, and 0.020% or less N by mass %, theremainder being Fe and inevitable impurities

{2} In the ferritic stainless steel sheet specified in item {1}, thecontent of Ti and the content of Nb satisfy the following inequality (1)

0.10≦Nb/Ti≦0.30   (1)

where the symbol for each of elements in Inequality (1) represents thecontent of a corresponding one of the elements.

{3} The ferritic stainless steel sheet specified in Item {1} or {2}further contains one or more selected from 0.01% to 0.30% Mo, 0.01% to0.50% Cu, 0.01% to 0.50% Co, and 0.01% to 0.50% W by mass %.

{4} The ferritic stainless steel sheet specified in Items (1) to (3)further contains one or more selected from 0.01% to 0.25% V, 0.01% to0.30% Zr, 0.0003% to 0.0030% B, 0.0005% to 0.0030% Mg, 0.0003% to0.0030% Ca, 0.001% to 0.20% Y, and 0.001% to 0.10% of a REM (rare-earthelement) by mass %.

{5} The ferritic stainless steel sheet specified in Items {1} to {4}further contains one or more selected from 0.001% to 0.50% Sn and 0.001%to 0.50% Sb by mass %.

{6} The ferritic stainless steel sheet specified in Items {1} to {5}containing 0.01% to 0. 25% V by mass %. The content of Ti and thecontent of Nb satisfy the following inequality (1) and the content ofTi, the content of Nb, and the content of V satisfy the followinginequality (2):

0.10≦Nb/Ti≦0.30   (1)

0.20≦V/(Ti+Nb)≦1.00   (2)

where the symbol for each of elements in Inequalities (1) and (2)represents the content of a corresponding one of the elements.

Advantageous Effects

A ferritic stainless steel sheet according to the disclosed embodimentsis excellent in corrosion resistance and workability. In particular,according to the disclosed embodiments, a ferritic stainless steelhaving excellent workability equal to or better than SUH409L andexcellent corrosion resistance is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the influence of the content of Ti and thecontent of Nb on corrosion resistance.

FIG. 2 is a graph showing the influence of the content of Ti, thecontent of Nb, and the content of V on corrosion resistance.

DETAILED DESCRIPTION

Disclosed embodiments are described below. The disclosed embodiments arenot limited to the embodiments below.

A ferritic stainless steel sheet according to the disclosed embodimentscontains 0.025% or less C, 0.01% to 1.00% Si, 0.05% to 1.00% Mn, 0.020%to 0.040% P, 0.030% or less S, 001% to 0.100% Al, 12.5% to 14 4% Cr,0.01% to 0.80% Ni, 0.11% to 0.40% Ti, 0.010% to 0.100% Nb, and 0.020% orless N by mass %.

In descriptions below, the unit “%” used to express components of theferritic stainless steel sheet refers to mass percent unless otherwisespecified.

C: 0.025% or less

C is an element effective in increasing the strength of steel. From theviewpoint of obtaining this effect, the content of C is preferably setto 0.001% or more. However, when the content of C is more than 0.025%,the corrosion resistance and the workability are significantlydeteriorated. Thus, the content of C is preferably set to 0.025% orless, more preferably 0.015% or less, and further more preferably 0.010%or less.

Si: 0.01% to 1.00%

Si is an element useful as a deoxidizing agent. This effect is obtainedwhen the content of Si is 0.01% or more. However, when the content of Siis more than 1.00%,the workability deteriorated because steel ishardened. Thus, the content of Si is limited to the range of 0.01% to1.00%. The content of Si preferably ranges from 0.03% to 0.50% and morepreferably 0.06% to 0.20%.

Mn: 0.05% to 1.00%

Mn has a deoxidizing effect. From the viewpoint of obtaining thiseffect, the content of Mn is set to 0.05% more. However, when thecontent of Mn is more than 1.00%, the corrosion resistance isdeteriorated because the precipitation and coarsening of MnS areprogressed. Thus, the content of Mn is limited to the range of 0.05% to1.00%. The content of Mn preferably ranges from 0.10% to 0.40% and morepreferably 0.20% to 0.30%.

P: 0.020% to 0.040%

P is an element deteriorating the corrosion resistance. Therefore, thecontent of P is preferably as low as possible and is set to 0.040% orless. However, excessively reducing the content of P to less than 0.020%causes an increase in steelmaking cost. Thus, the content of P islimited to the range of 0.020% to 0.040%. The content of P preferablyranges from 0.020% to 0.030%.

S: 0.030% or less

S forms a precipitate, MnS, with Mn. The interfaces between MnS and astainless steel base material serves as the origin of pitting, and itleads to deterioration of the corrosion resistance of a ferriticstainless steel. Thus, the content of S is preferably low and is set to0.030% or less. The content of S is preferably 0.020% or less and morepreferably 0.010% or less.

Al: 0.001% to 0.100%

Al is an element effective for deoxidizing. This effect is obtained whenthe content of Al is 0.001% or more. However, when the content of Al ismore than 0.100%, surface quality is deteriorated by the increase innumber of surface scratches due to aluminium non-metal inclusions. Thus,the content of Al is limited to the range of 0.001% to 0.100%. Thecontent of Al preferably ranges from 0.01% to 0.08% and more preferably0.02% to 0.06%.

Cr: 12.5% to 14.4%

Cr is an important element deciding the corrosion resistance andworkability of a ferritic stainless steel. The corrosion resistance ofthe ferritic stainless steel obtained because Cr forms a passive film onthe surface of steel. Therefore, increasing the content of Cr improvesthe corrosion resistance. In the disclosed embodiments, the content ofCr is adjusted to a specific range and the content of Ti and the contentof Nb are also adjusted to a specific range as described below, wherebythe corrosion resistance of steel is improved. In the disclosedembodiments, in order to obtain excellent corrosion resistance, thecontent of Cr needs to be 12.5% or more. However, easing the content ofCr deteriorates the workability of the ferritic stainless steel. In thedisclosed embodiments, the workability is improved by containing Nb asdescribed below. In the disclosed embodiments, in order to obtainworkability equal to or better than SUH409L, 14.4% or less Cr may becontained. Thus, the content of Cr is limited to the range of 12.5% to14.4%. The content of Cr preferably ranges from 13.0% to 13.8%.

Ni: 0.01% to 0.80%

Ni is an element which enables passive state to be maintained even at alower pH by suppressing an anodic reaction caused by acid. That is, Nihas the effect of improving the crevice corrosion resistance andsignificantly suppressing the progress of corrosion in an activedissolution state. This effect improves the corrosion resistance of theferritic stainless steel.

This effect is obtained when the content of Ni is 0.01% or more.However, when the content of Ni is more aan 0.80%, the workability isdeteriorated because steel is hardened. Thus, the content of Ni islimited to the range of 0.01% to 0.80%. The content of Ni preferablyranges from 0.10% to 0.40%.

Ti: 0.11% to 0.40%

Ti is an element which improves the corrosion resistance, since itprevents the occurrence of sensitization by fixing C and N as Crcarbonitrides. Furthermore, Ti further improves the corrosion resistanceby a combined effect with Nb as described below.

This effect is obtained when the content of Ti is 0.11% or more.However, when the content of Ti is more than 0.40%, the workability isdeteriorated because a stainless steel sheet is hardened. Furthermore,the quality of the surface is deteriorated by the formation of Tiinclusions on a surface. Thus, the content of Ti ranges preferably from0.11% to 0.40% and more preferably 0.20% to 0.35%.

Nb: 0.010% to 0.100%

Nb has the effect of fining its crystal gains by existing as solidsolution in steel, {111}-oriented grains are likely to be formed fromthe local areas near grain boundaries, the proportion of recrystallizedgrains in the {111} plane increases in the recrystallization process dueto fining crystal grain by containing Nb. Since this suppresses theformation of the Goss ({110} <001>-oriented grains, which deterioratesthe workability by increasing in-plane anisotropy, the in-planeanisotropy of a microstructure is reduced. As a result, El_(min) (theminimum among the elongation in an L-direction that is a rollingdirection, the elongation in a D-direction that is a 45-degree directionto the rolling direction, and the elongation in a C-direction that is adirection perpendicular to the rolling direction) and r_(min) (theminimum among the r-value in the L-direction, the r-value in theD-direction, and the r-value in the r-direction) are increased and, as aresult, the workability is improved. Furthermore, Nb further improvesthe corrosion resistance by a combined effect with Ti as describedbelow. This effect is obtained when the content of Nb is 0.010% or more.However, when the content of Nb is more than 0.100%, the workability isdeteriorated because the ferritic stainless steel is hardened. Thus, thecontent of Nb preferably ranges from 0.010% to 0.100% and morepreferably 0.030% to 0.070%.

Upon completing the disclosed embodiments, it was found that thecorrosion resistance can be improved by containing Ti and Nb incombination. The mechanism is probably as described below. It is knownthat the corrosion of stainless steels is caused by the local fractureof passive film, which is called pitting. A cause of pitting is localcrevice corrosion in crevices formed near surfaces of interfaces betweeninclusions and a steel base material because of the difference betweenthe strain applied to the inclusions and the strain applied to the steelbase material during working including rolling. MnS and Ti carbonitridesare typical examples of inclusions forming such crevices. Among these,Ti carbonitrides are relatively coarse, and the shape of the interfacesbetween Ti carbonitrides and steel base material are relatively linear.Therefore, an anodic reaction occurs intensively in crevices formed atthe interfaces. As a result of that, the corrosion resistance of steelis deteriorated. However, it has become clear that containing Ti and Nbin combination makes Nb carbonitrides to adhere to the peripheries ofthe Ti carbonitrides, thereby precipitating Ti—Nb compositecarbonitrides. Unlike the Ti carbonitrides, interfaces between the Ti—Nbcomposite carbonitrides obtained thereby and a stainless steel basematerial are not linear. That is, the interfaces have an increasedlength and therefore the anodic reaction occurs dispersively. Hence, thecorrosion resistance is improved because pitting is unlikely to occur.

In order to obtain this effect and in order to achieve good workability,the content of each of Ti and Nb needs to be within the above range. Theratio (Nb/Ti) of the content of Nb to the content of Ti preferablyranges from 0.10 to 0.30, This allows the corrosion resistance to befurther improved. When the ratio (Nb/Ti) is 0.10 or more, theprecipitation of the Nb carbonitrides near the Ti carbonitrides issufficient. When the ratio (Nb/Ti) is 0.30 or less, the Nb carbonitridesalone are unlikely to precipitate and the Ti—Nb composite carbonitridesare likely to be formed.

N: 0.020% or less

N is an element inevitably trapped in steel. When the content of N ismore than 0.020%, the corrosion resistance and the workability aresignificantly deteriorated. Thus, the content of N is set to 0.020% orless. The content of N is preferably 0.015% or less.

Essential components have been described above the disclosedembodiments, other elements below may be appropriately contained.

Mo: 0.01% to 0.30%

Mo has the effect of improving the crevice corrosion resistance of theferritic stainless steel. This effect is obtained when the content of Mois 0.01% or more. However, when the content of Mo is more than 0.30%,this effect is saturated and the workability is deteriorated. Therefore,in the case of containing Mo, the content of Mo is set to 0.01% to0.30%. The content of Mo is preferably 0.03% to 0.10%.

Cu: 0.01% to 0.50%

Cu has the effect of improving the toughness of steel. This effect isobtained when the content of Cu is 0.01% or more. However, when thecontent of Cu is more than 0.50%, the workability is deterioratedbecause the toughness of steel is deteriorated. Therefore, in the caseof containing Cu, the content of Cu is set to 0.01% to 50%. The contentof Cu is preferably 0.01% to less than 0.10% and more preferably 0.03%to 0.06%.

Co: 0.01% to 0.50%

Co is an element which improves the crevice corrosion resistance ofstainless steels. This effect is obtained when the content of Co 0.01%or more. However, when the content of Co is more than 0.50%, this effectis saturated and the workability is deteriorated. Therefore, in the caseof containing Co, the content of Co is set to 0.01% to 0.50%. Thecontent of Co preferably ranges from 0.03% to 0.30% and more preferably0.05% to 0.10%.

W: 0.01% to 0.50%

W is an element which improves the crevice corrosion resistance of theferritic stainless steel. In order to obtain this effect, the content ofW is preferably 0.01% or more. However, when the content is more than0.50%, this effect is saturated and the workability is deteriorated.Therefore, in the case of containing W, the content of W is set to 0.01%to 0.50%. The content of W preferably ranges from 0.03% to 0.30% andmore preferably 0.05% to 0.10%.

V: 0.01% to 0.25%

V is an element which mproves the crevice corrosion resistance of theferritic stainless steel. This effect is obtained when the content of Vis 0.01% or more. However, when the content of more than 0.25%, thiseffect is saturated and the workability is deteriorated. Therefore, thecontent of V is limited to the range of 0.01% to 0.25%. The content of Vpreferably ranges from 0.03% to 0.20% and more preferably 0.05% to0.10%.

Upon completing the disclosed embodiments, it was found that, in thecase of adding V, the effect of improving the corrosion resistance bycontaining Ti and Nb in combination is enhanced by adjusting the contentof V with respect to the sum of the content of Ti and the content of Nb.The mechanism is not clear but is probably as described below.

When V is contained in steel, carbonitrides of Ti and Nb contain V;hence, composite carbonitrides ((Ti, V)(C, N)) of Ti and V, compositecarbonitrides ((Nb, V) (C, N)) of Nb and V, and composite carbonitrides((Ti, Nb, V) (C, N)) that are the above Ti—Nb composite carbonitridesdoped with V are formed. Since these composite carbonitrides are formed,the peak precipitation temperature, that is the temperature at whichprecipitation is most promoted, decreases as compared to the case whereV is not contained. As a result, the grain growth of these compositecarbonitrides occurs at lower temperatures. Since diffusion is low in atemperature range, the coarsening of the carbonitrides is suppressed;hence, V-containing carbonitrides (that can be collectively referred toas Ti—Nb—V composite carbonitrides) have a small size relative to V-freeTi or Nb carbonitrides and composite carbonitrides of Ti and Nb (thatcan be collectively referred to as Ti—Nb composite carbonitrides) andform more dispersed precipitates. Since the composite carbonitrides aresmall in size, crevices formed between carbonitrides and a steel basematerial, during working including rolling are small. Therefore, localcrevice corrosion is unlikely to occur and the occurrence of pitting issuppressed. As a result, the corrosion resistance is improved.

In order to obtain this effect to achieve excellent corrosion resistanceand good workability, the content of each of Ti, Nb, and V is adjustedto the above range, the ratio (Nb/Ti) of the content of Nb o the contentof Ti is set to range from 0.10 to 0.30, and the ratio (V/(Ti+Nb)) ofthe content of V to the sum of the content of Nb and the content of Tiis set to range from 0.20 to 1.00. This allows the corrosion resistanceto be further improved. When the ratio (V/(Ti+Nb)) is 0.20 or more, thereduction in precipitation temperature of (Ti, V) (C, V) and (Nb, V) (C,V) significant. When the ratio (V/(Ti+Nb)) is 1.00 or less, Vcarbonitrides alone are unlikely to precipitate and the Ti—Nb—Vcomposite carbonitrides are likely to be formed.

Zr: 0.01% to 0.30%

Zr, as well as Ti and Nb, has the effect of improving the corrosionresistance, since it prevents the occurrence of sensitization by fixingC and N as Cr carbonitrides. This effect is obtained when the content ofis 0.01% or more. However, when the content of Zr is more than 0.30%,surface scratches are generated by the formation f ZrO₂ and the like.Therefore, in the case of containing Zr, the content of Zr is set to0.01% to 0.30%. The content of Zr is preferably 0.01% to 0.20%.

B: 0.0003% to 0.0030%

B is an element improving the hot workability and the secondaryworkability. It is known that containing B is effective in Ti-addedsteel. This effect is obtained when the content of B is 0.0003% or more.However, when the content of B is more than 0.0030%, the workability isdeteriorated. Thus, in the case of containing B, the content of B set torange from 0.0003% to 0.0030%. The content of B preferably ranges from0.0010% to 0.0025% and more preferably 0.0015% to 0.0020%.

Mg: 0.0005% to 0.0030%

Mg, as well as Al, acts as a deoxidizing agent by forming Mg oxides inmolten steel. This effect is obtained when the content of Mg is 0.0005%or more. However, when the content of Mg is more than 0.0030%, theproductivity is reduced because the toughness of steel is deteriorated.Thus, in the case of containing Mg, the content of Mg is limited to therange of 0.0005% to 0.0030%.

Ca: 0.0003% to 0.0030%

Ca is an element effective in preventing nozzles from being blocked bythe precipitation of Ti inclusions likely to be caused during continuouscasting. This effect is obtained when the content of Ca is 0.0003% ormore. However, when the content of Ca is more than 0.0030%, theproductivity is reduced because the toughness of steel is deteriorated.Furthermore, when the content of Ca is more than 0.0030%, the corrosionresistance is deteriorated by the precipitation of CaS. Thus, in thecase of containing Ca, the content of Ca is limited to the range of0.0003% to 0.0030%. The content of Ca preferably ranges from 0.0010% to0.0020%.

Y: 0.001% to 0.20%

Y is an element which improves the cleanliness of steel by reducing theviscosity of molten steel. This effect is obtained when the content of Yis 0.001% or more. However, when the content of Y is more than 0.20%,this effect is saturated and the workability is deteriorated. Therefore,in the case of containing Y, the content of Y limited to the range of0.001% to 0.20%. The content of Y preferably ranges from 0.001% to0.10%.

REM (rare-earth metal): 0.001% to 0.10%

REMs (rare-earth metals: elements, such as La, Ce, and Nd, having atomicnumbers 57 to 71) are elements which improve the high-temperatureoxidation resistance. This effect is obtained when the content of a REMis 0.001% or more. However, when the content of the REM is more than0.10%, this effect is saturated and surface scratches are caused duringhot rolling. Therefore, in the case of containing the REM, the contentof the REM is limited to the range of 0.001% to 0.10%. The content ofthe REM preferably ranges from 0.005% to 0.05%.

Sn, Sb: 0.001% to 0.50%

These elements are effective in improving the ridging resistance bypromoting the formation of deformed zones during rolling. This effect isobtained when the content of either of these elements is 0.001% or more.However, when the content of each of these elements more than 0.50%,this effect is saturated and the workability is deteriorated. Therefore,in the case of containing Sn and Sb, the content of each of Sn and Sb isset to 0.001% to 0.50%. The content of each of Sn and Sb preferablyranges from 0.003% to 0.20%.

The remainder other than the above components are inevitable impurities.

A preferable method for manufacturing the ferritic stainless steel sheetaccording to the disclosed embodiments is described below. Steel havingthe above composition is produced in a steel converter, an electricfurnace, a vacuum melting furnace, or the like by a known process and isthen formed into a steel material (slab) by a continuous casting processor an ingot casting-blooming process. After being heated to 1,000° C. to1,200° C., the steel material is hot-rolled at a finish temperature of700° C. to 1,000° C. such that the thickness is 2.0 mm to 5.0 mm. Ahot-rolled steel plate prepared as described above is annealed at atemperature of 800° C. to 1,100° C., is pickled, and is thencold-rolled. A cold-rolled steel sheet is annealed at a temperature of700° C.’ to 1,000° C. The annealed cold-rolled steel sheet is descaledby pickling. The descaled cold-rolled steel sheet may be subjected toskin-pass rolling.

EXAMPLES

Each of stainless steels having a composition shown in Nos. 1 to 82 inTable 1 (Tables 1-1, 1-2, and 1-3 are collectively referred to asTable 1) was produced in a vacuum melting furnace and was then cast intoa 30 kg steel ingot. After the steel ingot was heated to a temperatureof 1,050° C., the steel ingot was hot-rolled at a finish temperature of900° C., whereby a hot-rolled steel plate with a thickness of 5 mm wasobtained. Thereafter, the hot-rolled steel plate was annealed at 1,000°C. to 1,050° C. for 1 minute in an Ar atmosphere, was pickled insulfuric acid, and was then cold-rolled into a cold-rolled steel sheetwith a thickness of 1.0 mm. The obtained cold-rolled steel sheet wasannealed at 900° C. for 1 minute in an Ar atmosphere and was thenpickled by neutral-salt electrolysis, nitric hydrofluoric acidimmersion, and nitrate electrolysis, whereby a cold-rolled, annealed,and pickled steel sheet was obtained.

Each of ferritic stainless steels having a composition shown in Nos. 83and 84 in Table 1 was produced in a vacuum melt furnace and was thencast into a 30 kg steel ingot. After the steel ingot was heated to atemperature of 1,050° C., the steel ingot was hot-rolled at a finishtemperature of 900° C., whereby a hot-rolled steel plate with athickness of 5 mm was obtained. Thereafter, the hot-rolled steel platewas annealed at 800° C. to 850° C. for 12 hours in air, was pickled insulfuric acid, and was then cold-rolled into a cold-rolled steel sheetwith a thickness of 1.0 mm. The obtained cold-rolled steel sheet wasannealed at 800° C. for 1 minute in an Ar atmosphere and was thenpickled by neutral-salt electrolysis, nitric hydrofluoric acidimmersion, and nitrate electrolysis, whereby a cold-rolled, annealed,and pickled steel sheet was obtained.

Test Nos. 82 and 83 in Table 1 are steel corresponding to SUH4091, andsteel corresponding to SUS430, respectively.

The cold-rolled, annealed, and pickled steel sheets, which were obtainedfrom the ferritic stainless steels under the above manufacturingconditions, were cut to 80 mm×60 mm by shearing. After cutting,polishing was performed using emery paper up to 320 grade and degreasingwas performed using acetone. End portions and the back surface of eachobtained steel sheet were sealed, followed by placing the steel sheet ina corrosion testing device at an inclination of 60°. In the corrosiontesting device, a corrosion test was performed for 240 cycles in such amanner that spraying an aqueous solution containing 0.1% by mass NaCland 0.5% by mass H₂O₂ (30 minutes, 35° C., 98% RH (humidity)), drying (1hour, 60° C., 30% RH), and wetting (1 hour, 40° C., 95% RH) wereperformed in each cycle. This is a corrosion acceleration test methodfor evaluating the corrosion resistance of low- to medium-Cr steels.After the test, corrosion products were removed using a 10% di-ammoniumhydrogen citrate solution and the corrosion weight loss was measured.One with a corrosion weight loss of 1.0 g/m² or less was rated “A:⊚”(acceptable, very excellent), one with a corrosion weight loss of morethan 1.0 g/m² to 5.0 g/m² was rated “B:◯” (acceptable, particularlyexcellent), one with a corrosion weight loss of more than 5.0 g/m² to8.0 g/m² was rated “C:□” (acceptable, excellent), one with a corrosionweight loss of more than 8.0 g/m² to 16.0 g/m² was rated “D:Δ”(acceptable), and one with a corrosion weight loss of more than 16.0g/m² was rated “E:▴” (unacceptable).

Furthermore, No. 13D test specimens specified in JIS 2201 were sampledin a rolling direction, a 45-degree direction to the rolling direction,and a direction perpendicular to the rolling direction and weresubjected to a tensile test at room temperature, whereby the workabilitywas evaluated. One with an El_(min) of 33% or more and an r_(min) of 1.1or more was rated “A:∘” (acceptable) and one with an El_(min) of lessthan 33% or an r_(min) of less than 1.1 was rated “B:▴” (unacceptable).

Obtained results are shown in Table 1. Test Nos. 1 to 65, which aresteels according to the disclosed embodiments, have a rating of “B:∘”,“C:””, or “D:Δ” for corrosion resistance and a rating of “A:∘” forworkability. It is clear that Test Nos. 1 to 65 are excellent incorrosion resistance and workability. In particular, Test Nos. 34 to 47and 55 to 65, in which the ratio (V/(Ti+Nb)) satisfies the range of 0.20to 1.00 and which are steels according to the disclosed embodiments,have a rating of “B: ∘” for corrosion resistance and a rating of “A:∘”for workability.

FIG. 1 is a graph summarizing results of examples according to thedisclosed embodiments, results of comparative examples in which thecontent of Ti is outside the scope of the disclosed embodiments, andresults of comparative examples in which the content of Nb is outsidethe scope of the disclosed embodiments. As is clear from FIG. 1, in thecase where the content of Ti and the content of Nb satisfy Inequality(1), better corrosion resistance is exhibited.

FIG. 2 is a graph summarizing results of corrosion resistance in termsof the content of V and the sum of the content of Ti and the content ofNb for the examples according to the disclosed embodiments, in which thecontent of Ti and the content of Nb satisfy Inequality (1). As is clearfrom FIG. 2, in the case where the content of Ti, the content of Nb, andthe content of V satisfy Inequality (2), further better corrosionresistance is exhibited.

Test Nos. 34 to 47 and 55 to 65, in which the ratio (V/(Ti+Nb))satisfies the range of 0.20 to 1.00 and which are steels according tothe disclosed embodiments, have a rating of “B:∘” for corrosionresistance and a rating of “A:∘” for workability.

Test Nos. 66, 68, 70, and 71, which are comparative examples, have a Crcontent, Ni content, and Ti content lower than the scope of thedisclosed embodiments and therefore are deteriorated in corrosionresistance. Test Nos. 67, 69, 72, 73, 76, 77, 78, 79, and 80, which arecomparative examples, have a Cr content, Ni content, Ti content, Nbcontent, and V content higher than the scope of the disclosedembodiments and therefore are deteriorated in workability. Test Nos. 74and 75, which are comparative examples, have a Nb content lower than thescope of the disclosed embodiments and therefore are deteriorated incorrosion resistance and workability. Test No. 81, which is acomparative example, has a C content higher than the scope of thedisclosed embodiments and therefore is deteriorated in corrosionresistance and workability. Test No. 82, which is a comparative example,contains no Nb, has a Cr content lower than the scope of the disclosedembodiments, and therefore is deteriorated in corrosion resistance. TestNos. 83 and 84, which are comparative examples, contain no Nb; have a Ccontent, N content, and Cr content higher than the scope of thedisclosed embodiments and therefore are deteriorated in workability.

TABLE 1-1 Composition (mass percent) Test No. C Si Mn P S Al Cr Ni Ti NbN 1 0.007 0.08 0.24 0.024 0.010 0.034 12.6 0.44 0.26 0.044 0.011 2 0.0080.07 0.25 0.025 0.008 0.026 13.2 0.36 0.25 0.068 0.010 3 0.010 0.10 0.220.025 0.012 0.031 13.8 0.44 0.28 0.060 0.010 4 0.008 0.10 0.22 0.0230.011 0.031 14.4 0.35 0.29 0.049 0.013 5 0.011 0.12 0.25 0.026 0.0110.034 13.6 0.04 0.29 0.064 0.012 6 0.007 0.09 0.25 0.028 0.009 0.03313.5 0.78 0.23 0.065 0.012 7 0.011 0.09 0.21 0.024 0.010 0.026 13.5 0.430.11 0.051 0.008 8 0.012 0.11 0.23 0.027 0.008 0.032 13.5 0.35 0.380.062 0.012 9 0.008 0.10 0.25 0.020 0.009 0.031 13.3 0.40 0.25 0.0120.008 10 0.009 0.12 0.24 0.028 0.008 0.032 13.2 0.36 0.28 0.097 0.009 110.007 0.07 0.20 0.027 0.008 0.026 13.3 0.38 0.39 0.094 0.012 12 0.0070.13 0.22 0.022 0.008 0.032 13.6 0.39 0.35 0.096 0.008 13 0.011 0.080.24 0.023 0.011 0.032 13.1 0.42 0.13 0.029 0.008 14 0.010 0.13 0.230.023 0.010 0.031 13.7 0.36 0.11 0.012 0.012 15 0.012 0.08 0.25 0.0230.011 0.028 13.4 0.36 0.38 0.040 0.007 16 0.008 0.08 0.21 0.028 0.0110.033 13.6 0.37 0.13 0.086 0.013 17 0.008 0.07 0.22 0.023 0.011 0.02913.4 0.38 0.38 0.013 0.012 18 0.010 0.13 0.23 0.027 0.012 0.031 13.60.37 0.13 0.011 0.008 19 0.007 0.11 0.21 0.024 0.012 0.028 13.3 0.410.39 0.035 0.007 20 0.010 0.27 0.23 0.031 0.008 0.029 13.1 0.43 0.180.061 0.010 21 0.007 0.34 0.23 0.028 0.011 0.033 13.4 0.35 0.25 0.0800.010 22 0.009 0.27 0.20 0.033 0.011 0.026 13.7 0.43 0.28 0.025 0.009 230.009 0.12 0.24 0.022 0.012 0.028 13.3 0.39 0.14 0.016 0.008 24 0.0080.12 0.24 0.021 0.009 0.030 13.6 0.36 0.25 0.036 0.010 25 0.011 0.090.20 0.022 0.010 0.032 13.7 0.43 0.27 0.052 0.011 26 0.007 0.14 0.220.027 0.008 0.035 13.5 0.39 0.29 0.056 0.008 27 0.008 0.06 0.21 0.0260.008 0.034 13.3 0.37 0.28 0.031 0.011 28 0.011 0.06 0.20 0.023 0.0100.030 13.1 0.40 0.23 0.037 0.009 29 0.009 0.14 0.20 0.023 0.011 0.02913.8 0.41 0.20 0.041 0.013 30 0.009 0.13 0.25 0.024 0.009 0.033 13.30.40 0.29 0.069 0.008 31 0.013 0.08 0.24 0.025 0.010 0.030 13.5 0.360.27 0.044 0.011 32 0.009 0.08 0.24 0.022 0.008 0.035 13.2 0.39 0.290.050 0.007 33 0.010 0.11 0.23 0.028 0.011 0.034 13.2 0.39 0.25 0.0560.010 Properties Composition (mass percent) Corrosion Test No. Otherelements Nb/Ti V/(Ti + Nb) resistance Workability 1 0.17 — C: □ A: ◯Example 2 0.27 — C: □ A: ◯ Example 3 0.21 — C: □ A: ◯ Example 4 0.17 —C: □ A: ◯ Example 5 0.22 — C: □ A: ◯ Example 6 0.28 — C: □ A: ◯ Example7 0.46 — D: Δ  A: ◯ Example 8 0.16 — C: □ A: ◯ Example 9 0.05 — D: Δ  A:◯ Example 10 0.35 — D: Δ  A: ◯ Example 11 0.24 — C: □ A: ◯ Example 120.27 — C: □ A: ◯ Example 13 0.22 — C: □ A: ◯ Example 14 0.11 — C: □ A: ◯Example 15 0.11 — C: □ A: ◯ Example 16 0.66 — D: Δ  A: ◯ Example 17 0.03— D: Δ  A: ◯ Example 18 0.08 — D: Δ  A: ◯ Example 19 0.09 — D: Δ  A: ◯Example 20 0.34 — D: Δ  A: ◯ Example 21 0.32 — D: Δ  A: ◯ Example 220.09 — D: Δ  A: ◯ Example 23 V: 0.18, Co: 0.03, Cu: 0.04, Zr: 0.04, 0.111.15 C: □ A: ◯ Example Mo: 0.05, W: 0.03 24 B: 0.0016, Mg: 0.002, Ca:0.002 0.14 — C: □ A: ◯ Example 25 Y: 0.06, La: 0.04 0.19 — C: □ A: ◯Example 26 Sn: 0.05 0.19 — C: □ A: ◯ Example 27 Sb: 0.03 0.11 — C: □ A:◯ Example 28 V: 0.02, B: 0.0013 0.16 0.07 C: □ A: ◯ Example 29 Cu: 0.06,Y: 0.08 0.21 — C: □ A: ◯ Example 30 Zr: 0.08, Sn: 0.15 0.24 — C: □ A: ◯Example 31 Co: 0.10, Nd: 0.03, Sb: 0.11 0.16 — C: □ A: ◯ Example 32 Mo:0.07, Ca: 0.001 0.17 — C: □ A: ◯ Example 33 W: 0.06, Co: 0.21, Ce:0.004, Sn: 0.34 0.22 — C: □ A: ◯ Example * [Corrosion resistance] After240 cycles of a corrosion test, one with a corrosion weight loss of 1.0g/m² or less was rated “A: ⊚” (acceptable, very excellent), one with acorrosion weight loss of more than 1.0 g/m² to 5.0 g/m² was rated “B: ◯”(acceptable, particularly excellent), one with a corrosion weight lossof more than 5.0 g/m² to 8.0 g/m² was rated “C: □” (acceptable,excellent), one with a corrosion weight loss of more than 8.0 g/m² to16.0 g/m² was rated “D: Δ” (acceptable), and one with a corrosion weightloss of more than 16.0 g/m² was rated “E” (unacceptable). *[Workability] By a room-temperature tensile test, one with an El_(min)of 33% or more and an r_(min) of 1.1 or more was rated “A: ◯”(acceptable) and one with an El_(min) of less than 33% or an r_(min) ofless than 1.1 was rated “B: ▴” (unacceptable). * Underlined values areoutside the scope of the disclosed embodiments.

TABLE 1-2 Composition (mass percent) Test No. C Si Mn P S Al Cr Ni Ti NbN 34 0.010 0.06 0.24 0.027 0.011 0.032 13.7 0.37 0.11 0.022 0.009 350.008 0.07 0.23 0.023 0.009 0.029 13.2 0.37 0.38 0.063 0.011 36 0.0130.11 0.21 0.025 0.010 0.028 13.7 0.39 0.12 0.012 0.009 37 0.012 0.090.23 0.025 0.010 0.030 13.5 0.45 0.33 0.096 0.010 38 0.007 0.07 0.230.021 0.012 0.035 13.2 0.40 0.12 0.014 0.013 39 0.010 0.12 0.23 0.0240.012 0.029 13.6 0.44 0.35 0.075 0.013 40 0.007 0.08 0.21 0.022 0.0120.030 13.3 0.43 0.23 0.032 0.009 41 0.009 0.06 0.21 0.024 0.008 0.02813.3 0.43 0.11 0.012 0.009 42 0.011 0.10 0.24 0.023 0.010 0.033 13.00.38 0.11 0.014 0.007 43 0.010 0.08 0.23 0.021 0.011 0.031 13.3 0.370.39 0.084 0.012 44 0.012 0.12 0.26 0.025 0.010 0.034 13.6 0.44 0.380.096 0.007 45 0.011 0.25 0.22 0.032 0.011 0.034 13.6 0.37 0.19 0.0260.008 46 0.012 0.32 0.22 0.031 0.009 0.028 13.2 0.37 0.18 0.051 0.013 470.009 0.27 0.26 0.031 0.009 0.026 13.0 0.42 0.28 0.068 0.012 48 0.0130.10 0.26 0.028 0.010 0.034 13.3 0.43 0.12 0.023 0.009 49 0.011 0.080.26 0.025 0.008 0.031 13.3 0.42 0.11 0.014 0.010 50 0.010 0.08 0.250.026 0.010 0.026 13.0 0.45 0.19 0.042 0.007 51 0.012 0.12 0.22 0.0240.009 0.026 13.1 0.39 0.13 0.022 0.011 52 0.008 0.12 0.22 0.026 0.0090.026 13.1 0.36 0.36 0.093 0.007 53 0.008 0.12 0.24 0.026 0.009 0.02613.5 0.38 0.37 0.086 0.012 54 0.009 0.28 0.25 0.028 0.008 0.029 13.00.38 0.26 0.036 0.009 55 0.012 0.06 0.24 0.026 0.011 0.031 13.3 0.450.22 0.064 0.012 56 0.011 0.10 0.23 0.027 0.011 0.029 13.2 0.38 0.280.047 0.010 57 0.010 0.09 0.24 0.026 0.012 0.028 13.2 0.42 0.28 0.0580.011 58 0.010 0.09 0.20 0.023 0.010 0.035 13.1 0.35 0.25 0.031 0.012 590.010 0.12 0.23 0.020 0.011 0.027 13.2 0.39 0.20 0.045 0.007 60 0.0090.09 0.23 0.024 0.011 0.030 13.1 0.43 0.21 0.031 0.008 61 0.011 0.140.26 0.028 0.011 0.029 13.1 0.42 0.23 0.046 0.007 62 0.010 0.07 0.240.021 0.009 0.027 13.3 0.45 0.28 0.031 0.010 63 0.010 0.12 0.21 0.0270.012 0.026 13.1 0.38 0.27 0.066 0.011 64 0.012 0.11 0.21 0.023 0.0100.034 13.6 0.42 0.23 0.034 0.011 65 0.012 0.08 0.23 0.021 0.008 0.03113.3 0.42 0.26 0.035 0.009 Properties Composition (mass percent)Corrosion Test No. Other elements Nb/Ti V/(Ti + Nb) resistanceWorkability 34 V: 0.04 0.20 0.30 B: ◯ A: ◯ Example 35 V: 0.17 0.17 0.38B: ◯ A: ◯ Example 36 V: 0.05 0.10 0.38 B: ◯ A: ◯ Example 37 V: 0.18 0.290.42 B: ◯ A: ◯ Example 38 V: 0.03 0.12 0.22 B: ◯ A: ◯ Example 39 V: 0.240.21 0.56 B: ◯ A: ◯ Example 40 V: 0.24 0.14 0.92 B: ◯ A: ◯ Example 41 V:0.11 0.11 0.90 B: ◯ A: ◯ Example 42 V: 0.03 0.13 0.24 B: ◯ A: ◯ Example43 V: 0.11 0.22 0.23 B: ◯ A: ◯ Example 44 V: 0.25 0.25 0.53 B: ◯ A: ◯Example 45 V: 0.17 0.14 0.79 B: ◯ A: ◯ Example 46 V: 0.05 0.28 0.22 B: ◯A: ◯ Example 47 V: 0.09 0.24 0.26 B: ◯ A: ◯ Example 48 V: 0.24 0.19 1.68C: □  A: ◯ Example 49 V: 0.14 0.13 1.13 C: □  A: ◯ Example 50 V: 0.240.22 1.03 C: □  A: ◯ Example 51 V: 0.02 0.17 0.13 C: □  A: ◯ Example 52V: 0.08 0.26 0.18 C: □  A: ◯ Example 53 V: 0.01 0.23 0.02 C: □  A: ◯Example 54 V: 0.04 0.14 0.14 C: □  A: ◯ Example 55 V: 0.13, Co: 0.04,Cu: 0.03, Zr: 0.04, 0.29 0.46 B: ◯ A: ◯ Example Mo: 0.09, W: 0.09 56 V:0.13, B: 0.0015, Mg: 0.001, Ca: 0.17 0.40 B: ◯ A: ◯ Example 0.002 57 V:0.15, Y: 0.03, La: 0.04 0.21 0.44 B: ◯ A: ◯ Example 58 V: 0.16, Sn: 0.120.12 0.57 B: ◯ A: ◯ Example 59 V: 0.12, Sb: 0.14 0.23 0.49 B: ◯ A: ◯Example 60 V: 0.13, Cu: 0.05, Co: 0.06 0.15 0.54 B: ◯ A: ◯ Example 61 V:0.10, Zr: 0.02, Nd: 0.03 0.20 0.36 B: ◯ A: ◯ Example 62 V: 0.13, Mo:0.07, Sn: 0.03 0.11 0.42 B: ◯ A: ◯ Example 63 V: 0.16, B: 0.0012, Y:0.015, Sb: 0.10 0.24 0.48 B: ◯ A: ◯ Example 64 V: 0.11, Cu: 0.06, Ca:0.003, Sn: 0.07 0.15 0.42 B: ◯ A: ◯ Example 65 V: 0.13, Zr: 0.03, Mg:0.0009, Ce: 0.04 0.13 0.44 B: ◯ A: ◯ Example * [Corrosion resistance]After 240 cycles of a corrosion test, one with a corrosion weight lossof 1.0 g/m² or less was rated “A: ⊚” (acceptable, very excellent), onewith a corrosion weight loss of more than 1.0 g/m² to 5.0 g/m² was rated“B: ◯” (acceptable, particularly excellent), one with a corrosion weightloss of more than 5.0 g/m² to 8.0 g/m² was rated “C: □” (acceptable,excellent), one with a corrosion weight loss of more than 8.0 g/m² to16.0 g/m² was rated “D: Δ” (acceptable), and one with a corrosion weightloss of more than 16.0 g/m² was rated “E: ▴” (unacceptable). *[Workability] By a room-temperature tensile test, one with an El_(min)of 33% or more and an r_(min) of 1.1 or more was rated “A: ◯”(acceptable) and one with an El_(min) of less than 33% or an r_(min) ofless than 1.1 was rated “B: ▴” (unacceptable). * Underlined values areoutside the scope of the disclosed embodiments.

TABLE 1-3 Composition (mass percent) Properties Test Other V/(Ti +Corrosion Work- No. C Si Mn P S Al Cr Ni Ti Nb N elements Nb/Ti Nb)resistance ability 66 0.007 0.07 0.22 0.026 0.011 0.031 12.2 0.36 0.290.049 0.008 0.17 — E: ▴  A: ◯ Comparative example 67 0.008 0.07 0.210.023 0.009 0.029 14.7 0.40 0.27 0.068 0.009 0.25 —  B: ◯ B: ▴Comparative example 68 0.010 0.10 0.23 0.025 0.009 0.033 13.4 — 0.270.048 0.011 0.18 — E: ▴  A: ◯ Comparative example 69 0.009 0.06 0.230.028 0.012 0.028 13.3 0.84 0.29 0.050 0.013 0.17 —  B: ◯ B: ▴Comparative example 70 0.009 0.12 0.20 0.021 0.009 0.030 13.4 0.36 0.090.012 0.010 0.13 — E: ▴  A: ◯ Comparative example 71 0.008 0.09 0.210.024 0.009 0.025 13.0 0.42 0.08 0.098 0.010 1.23 — E: ▴  A: ◯Comparative example 72 0.011 0.12 0.23 0.021 0.012 0.035 13.7 0.45 0.420.014 0.008 0.03 — D: Δ  B: ▴ Comparative example 73 0.007 0.11 0.210.022 0.008 0.031 13.4 0.41 0.44 0.093 0.012 0.21 — C: □ B: ▴Comparative example 74 0.010 0.06 0.24 0.027 0.011 0.028 13.4 0.35 0.130.005 0.007 0.04 — E: ▴ B: ▴ Comparative example 75 0.009 0.13 0.230.021 0.009 0.029 13.6 0.39 0.38 0.008 0.010 0.02 — E: ▴ B: ▴Comparative example 76 0.012 0.11 0.24 0.026 0.009 0.028 13.2 0.44 0.240.112 0.012 0.80 — D: Δ  B: ▴ Comparative example 77 0.010 0.13 0.240.027 0.011 0.031 13.5 0.38 0.35 0.103 0.011 0.29 — C: □ B: ▴Comparative example 78 0.009 0.07 0.23 0.020 0.009 0.026 13.4 0.41 0.120.015 0.009 V: 0.28 0.13 2.07 C: □ B: ▴ Comparative example 79 0.0110.13 0.24 0.021 0.010 0.031 13.0 0.39 0.21 0.044 0.009 V: 0.27 0.21 1.06C: □ B: ▴ Comparative example 80 0.011 0.10 0.21 0.021 0.009 0.033 13.70.36 0.34 0.086 0.008 V: 0.26 0.25 0.61  B: ◯ B: ▴ Comparative example81 0.030 0.10 0.23 0.026 0.008 0.034 13.2 0.36 0.26 0.057 0.008 0.22 —E: ▴ B: ▴ Comparative example 82 0.006 0.25 0.39 0.022 0.002 0.029 10.90.13 0.26 — 0.006 — — E: ▴  A: ◯ Comparative example 83 0.039 0.23 0.580.026 0.005 0.001 16.2 0.24 — — 0.046 — — A: ⊚ B: ▴ Comparative example84 0.041 0.25 0.38 0.026 0.004 0.001 15.1 0.16 — — 0.048 — — D: Δ  B: ▴Comparative example * [Corrosion resistance] After 240 cycles of acorrosion test, one with a corrosion weight loss of 1.0 g/m² or less wasrated “A: ⊚” (acceptable, very excellent), one with a corrosion weightloss of more than 1.0 g/m² to 5.0 g/m² was rated “B: ◯” (acceptable,particularly excellent), one with a corrosion weight loss of more than5.0 g/m² to 8.0 g/m² was rated “C: □” (acceptable, excellent), one witha corrosion weight loss of more than 8.0 g/m² to 16.0 g/m² was rated “D:Δ” (acceptable), and one with a corrosion weight loss of more than 16.0g/m² was rated “E: ▴” (unacceptable). * [Workability] By aroom-temperature tensile test, one with an El_(min) of 33% or more andan r_(min) of 1.1 or more was rated “A: ◯” (acceptable) and one with anEl_(min) of less than 33% or an r_(min) of less than 1.1 was rated “B:▴” (unacceptable). * Underlined values are outside the scope of thedisclosed embodiments.

INDUSTRIAL APPLICABILITY

The disclosed embodiments have excellent corrosion resistance andworkability and therefore can be preferably used for applications suchas inner panels for elevators, interiors, duct hoods, muffler cutters,lockers, home appliance parts, office equipment parts, automotiveinterior parts, automotive exhaust pipes, building materials, and coversfor drains.

1. A ferritic stainless steel sheet Comprising, by mass %: 0.025% orless C; 0.01% to 1.00% Si; 0.05% to 1.00% Mn; 0.020% to 0.040% P; 0.030%or less S; 0.001% to 0.100% Al; 12.5% to 14.4% Cr; 0.01% to 0.80% Ni;0.11% to to 0.40% Ti; 0.010% to 0.100% Nb; 0.020% or less N; and theremainder being Fe and inevitable impurities.
 2. The ferritic stainlesssteel sheet according to claim 1, wherein the content of Ti and thecontent of Nb satisfy the following Inequality (1):0.10≦Nb/Ti≦0.30   (1) where Nb and Ti represent the content of eachrespective element.
 3. The ferritic stainless steel sheet according tofurther comprising at least one group selected from the followinggroups: Group A: one or more element selected from the group consistingof, by mass %, 0.01% to 0.30% Mo, 0.01% to 0.50% Cu, 0.01% to 0.50% Co,and 0.01% to 0.50% W, Group B: one or more element selected from thegroup consisting of, by mass %, 0.01% to (125% V, 0.01% to 0.30% Zr,0.0003% to 0.0030% B, 0.0005% to 0.0030% Mg, 0.0003% to 0.0030% Ca,0.001% to 0.20% Y, and 0.001% to 0.10% of a REM, and Group C: one ormore element selected from the group consisting of, by mass %, 0.001.%to 0.50% Sn and 0.001% to 0.530% Sb.
 4. The ferritic stainless steelsheet according claim 2, further comprising at lest one group selectedfrom the following groups: Group A: one or more element selected fromthe group consisting of, by mass % 0.01% to 0.30% Mo, 0.01% to 0.50% Cu,0.01% to 0.50% Co, and 0.01% to 0.50% W, Group B: one or more elementselected from the group consisting of, by mass %, 0.01% to (125% V,0.01% to 0.30% Zr, 0.0003% to 0.0030% B, 0.0005% to 0.0030% Mg, 0.0003%to 0.0030% Ca, 0.001% to 0.20% Y. and 0.001% to 0.10% of a REM, andGroup C: one or more element selected from the group consisting of, bymass %. 0.001.% to 0.50% Sn and 0.001% to 0.530% Sb.
 5. (canceled) 6.The ferritic stainless steel sheet according to claim 1, furthercomprising, by mass %, 0.01% to 0.25% V, wherein the content of Ti, thecontent of Nb, and the content of V satisfy the following Inequality (1)and Inequality (2):0.10≦Nb/Ti≦0.30   (1)0.20≦V/(Ti+Nb)≦1.00   (2) where Ti, Nb and V represent the content ofeach respective element.
 7. The ferritic stainless steel sheet accordingto claim 2, further comprising, by mass %, 0.01% to 0.25% V, wherein thecontent of Ti, the content of Nb, and the content of V satisfy thefollowing Inequality (2):0.20≦V/(Ti+Nb)≦1.00   (2) where Ti, Nb and V represent the content ofeach respective element.
 8. The ferritic stainless steel sheet accordingto claim 3, further comprising, by mass %, 0.01% to 0.25% V, wherein thecontent of Ti, the content of Nb, and the content of V satisfy thefollowing Inequality (1) and Inequality (2):0.10≦Nb/Ti≦0.30   (1)0.20≦V/(Ti+Nb)≦1.00   (2) where Ti, Nb and V represent the content ofeach respective element.
 9. The ferritic stainless steel sheet accordingto claim 4, further comprising, by mass %, 0.01% to 0.25% V, wherein thecontent of Ti, the content of Nb, and the content of V satisfy thefollowing Inequality (2):0.20≦V/(Ti+Nb)≦1.00   (2) where Ti, Nb and V represent the content ofeach respective element.